A376584 - OEIS

A376584

Fixed points in A375564.

1, 2, 3, 4, 15, 51, 63, 363, 437, 729, 1385, 1388, 1413, 2807, 5418, 5422, 5428, 5435, 5451, 5537, 10790, 10795, 10803, 10871, 21505, 21507, 21899, 22081, 42969, 43073, 43387, 44069, 171631, 172889, 342493, 2747813, 5464783, 10908941, 10911583, 87259373, 87327187, 174579089

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..42.

PROG

(Python)

from itertools import count, islice

from math import gcd

from sympy import isprime

def A376584_gen(): # generator of terms

aset, a, b = {1, 2}, 2, 3

yield from (1, 2)

for i in count(3):

c = b

if isprime(a):

while c in aset or gcd(c, a)>1:

c+=1

else:

while c in aset or gcd(c, a)==1:

c+=1

aset.add(a:=c)

if i == c:

yield i

while b in aset:

b += 1

A376584_list = list(islice(A376584_gen(), 20)) # Chai Wah Wu, Sep 30 2024

CROSSREFS

Cf. A375564, A376189, A376191, A376192, A376193, A376195.

Sequence in context: A005645 A362639 A348628 * A281586 A365739 A217714

Adjacent sequences: A376581 A376582 A376583 * A376585 A376586 A376587

KEYWORD

nonn

AUTHOR

Scott R. Shannon, Sep 29 2024

EXTENSIONS

a(40)-a(42) from Scott R. Shannon, Oct 02 2024

STATUS

approved